Greenhouse is climate controlled transparent chamber made of materials like polycarbonate, in which crops are grown under controlled climatic conditions. This research paper aims to present a design of low-cost IoT interfaced Greenhouse Control Unit, where microclimate is controlled using various sensors and actuators to maintain desired environmental conditions as per crop need. It is used in precision agricultural research to study the impact of environmental parameters like humidity, temperature, ambient light and soil moisture on crop yield and its nutritional components. Temperature, humidity, ambient light and soil moisture like parameters are fetched by deploying suitable sensors at suitable locations in the chamber, and based on predefined threshold values of these parameters switching of cooling, heating system, light, fogger, dehumidifiers, and irrigation system are controlled using embedded controller device and desired climatic condition is maintained inside the Greenhouse chamber for the required duration. Such control units are required for agricultural research to study the impact of environmental parameters on crop yield and on the nutritional contents of the crop. It is also used in producing medicinal and herbal plants in the region which climate is very harsh for these plants. Authors have developed a low-cost cloud interfaced standalone embedded control unit around ARM Cortex M3 CPU, various sensors for controlling greenhouse actuators based on pre-defined threshold values of environmental parameters.